q3fall2004_key4324

q3fall2004_key4324 - Quiz 3 EMA 4324, Stability of...

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EMA 4324, Stability of Materials, LecSec 3009 KEY Monday, October 11, 2004 Electrochemical data for the JRA - H 2 O system are presented on the following table. 1. [5 points] Assuming charge transfer [activation] control of all electrochemical processes, what values would you predict for the corrosion potential and corrosion current for JRA exposed to deaerated water of pH 3? [note: you may solve the problem using either analytical or graphical methods - I have provided a blank Evan’s diagram; the analytical expression[s] were in downloadable notes.] Corrosion current, i corr = 3.98x10 -4 A Corrosion potential, E corr = -0.392 v SHE 0.1 1x10 -15 1.053 O 2 + 2H 2 O + 4e - = 4OH - 0.06 1x10 -7 -0.178 2H + + 2e - = H 2 0.15 5x10 -5 -0.528 J +2 + 2e - = J Tafel constant, β , volts exchange current density, j o , A/cm 2 equilibrium [Nernst] potential, volts SHE process E o [J +2 /J] = -0.350 v; [J +2 ] = 10 -6 M; assume all j o values to have been determined at E N solution pH = 3 -0.40 -0.20 0.00
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This note was uploaded on 10/18/2011 for the course EMA 4324 taught by Professor Staff during the Fall '09 term at University of Florida.

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q3fall2004_key4324 - Quiz 3 EMA 4324, Stability of...

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